Plastic molded case halves with concealed interlock



y 1967 L. ca. WOERNER PLASTIC MOLDED CASE HALVES WITH CONCEALED INTERLOCK Filed Jan. 6, 1965 INVENTOR [[0 I I 0mm P m M ATTORNEY United States Patent 3,317,073 PLASTIC MOLDED CASE HALVES WITH CONCEALED INTERLOCK Leo G. Woerner, Lancaster, Pa., assignor to Schick Electric Inc., Lancaster, Pa., a corporation of Pennsylvania Filed Jan. 6, 1965, Ser. No. 423,658

1 Claim. (Cl. 220-4) The invention has to do with the securing together or interlocking, without the use of screws or the like, of the two secti-onsor halves as they will be termed-of plastic molded cases such as are used, for example, to house the motor and form the handle of an electric shaver. At the upper or head end, the two halves of a shaver case are commonly united by spring clips and the present invention is primarily concerned with the interlocking of the mating walls of the case halves at the opposite or bottom end of a shaver case or wherever analagous requirements are encountered.

The objects of the invention are to provide concealed interlocking means which require no separate components and can readily be molded integrally with the case halves, which are simple to manipulate and which incorporate special provision to ensure against tampering or inadvertent separation of the two molded sections. How these objects are achieved will be illustrated and described with reference to an electric shaver case.

In its preferred form the invention comprises a plastic case consisting of molded halves having mating end walls, a pair of spaced locking elements molded integrally with the face of the said end wall of one of the halves, said locking elements projecting beyond the edge of such end wall into the other case half adjacent the inner face of its mating end wall and having outwardly directed hook ends, the said inner wall face of said other case half having recesses spaced to receive the said hook ends of the locking elements and thereby interlock the said walls of the two halves against pull-apart separation, a keeper element molded integrally with said inner wall face of said other case half between its said recesses, said keeper element projecting into the first-mentioned case half between the locking elements and overlying the inner face of the end wall of such first-mentioned case half, whereby inward deflection of the end wall of the first-mentioned case half is transmitted through the keeper element to the end wall of said other case half to maintain the interlock of the said hook ends and recesses.

In the drawings:

FIG. 1 is a front elevation of an electric shaver case incoporating the preferred form of the invention;

FIG. 2 is a side elevation of the case;

FIG. 3 is a broken out expanded view of the lower end portions of the halves of the case;

FIG. 4 is an enlarged top plan view of the mating portions of the bottom (-or end walls, as they will be called) of the case;

FIG. 5 is a vertical section on the line 5-5 of FIG. 4 of the interlocked end walls and adjacent wall portions of the case;

FIG. 6 is a vertical section of a detail, on the line 66 of FIG. 4; and

FIG. 7 is a vertical section, on the scale of FIGS. 4-6, on the line 77 of FIG. 1.

The illustrated shaver case, generally designated -10, consists of sections or halves generally designated 11, 12 molded with suitably mating edges. As indicated in FIG. 4, these edges may be lap jointed, as at 13, so that when brought together they are interlocked against lateral or sliding separation-that is, in directions parallel to the plane of the parting line.

The invention is concerned with the interlocking, against 3,317,073 Patented May 2, 1967 "ice pull apart separation, of what in this instance are the bottom or end walls generally designated 14, 15.

End wall 15 has at least one locking element molded integrally with it and preferably two such elements, spaced apart, as shown at 20, 21, and for greater strength they are shown as being thicker than the adjacent end wall portions. These locking elements project beyond the edge of end wall 15 and are of such a length as to project into the other case half 14'adjacent its inner face 22. The free end of each locking element 20, 21 is formed as an outwardly directed hook 23, 24-that is, directed toward the outside of the case.

The inner face 22 of end wall 14 is formed with recesses 25, 26 to receive the hook ends 2 3, 24 to form an interlock against pull-apart separation, as shown in FIG. 6.

Looking at FIG. 6, it will be recognized that if finger pressure is applied to the outer side of end wall 15, the tendency will be to unlock the hook end 23 from its recess 25 and that such unlocking will result if the end wall 15 is so thin (as may be desirable for economy sake) as to be sufiiciently flexible as to permit it.

However, such unlocking is prevented by means of a suitable keeper element molded integrally with end wall 14 and designed to project into case half 12 and, by overlapping end wall 15, serve to transmit any inward deflection of that end wall to end wall 14 and thereby maintain the relative positions of the hooks and recesses in the respective case halves and hence maintain the interlock.

In this preferred form, a single keeper element 30 is shown, in the form of a flap projecting from end wall 14 and so disposed that, when the case halves are mated, it overlies the portion 31 of end wall 15. Accordingly, if inward pressure is applied to the outer side of wall 15, any resulting inward movement of that end wall causes flap 30 also to move inwardly and with it, of course, the adjacent or recessed portions of end wall 14, so that the hook ends continue in engagement in the recesses.

The upper ends of the case halves may be held together in any preferred or suitable manner. In the drawings, FIG. 7, upper end recesses 35, 36 are shown and a spring clip '37 engaged in the recesses and serving to hold the upper ends of the case halves together.

It will be understood that the case halves are assembled by bringing them together at their lower ends, with their upper ends spaced apart, and then closing them like a book so as to rotate the hook ends into the recesses. The upper end clip is then snapped into place. The case halves are then securely interlocked and cannot be separated without first removing the clip or such other means as are employed to hold the upper ends of the case halves together.

It will be noted that the interlock of the end walls is effected by means located wholly Within the case and hence out of sight, so that there is nothing to mar the outside appearance of the case.

It will be obvious that the specific form, number and disposition of the hook and keeper elements are subject to modification to meet the needs of the particular situation.

In the light of the foregoing description of the preferred form of the invention, the following is claimed.

I claim:

A plastic case for electric shavers and the like compris- (a) molded halves having abutting upper ends and mating side and lower end walls and means for locking such walls against lateral separation;

(b) manually releasable means adapted to secure the upper ends of the case halves against pull-apart separation;

(c) locking means independent of both said above-mentioned means for interlocking the lower ends only of the halves against pull-apart separation and including a locking element molded integrally with the inner face of the lower end wall of one of the halves;

(d) said locking element forming a projection extending beyond the adjacent edges of the end wall of which it is a part and in the direction and into the interior of the other case half adjacent the inner face of the lower end wall thereof;

(e) said independent locking means also including a keeper molded integrally with the inner face of the lower end wall of said other case half adjacent the said locking element;

(f) said keeper element forming a projection extending beyond the adjacent edges of the end wall of Which it is a part and in the direction and into the interior of the first-mentioned case half adjacent the inner face of the lower end wall thereof;

(g) the said locking element terminating within the said other case half in a downwardly directed hook and the inner face of the lower end Wall of the said other case half having an upwardly directed recess to re 'ceive said hook;

(h) said hook and recess being shaped to positively in- References Cited by the Examiner UNITED STATES PATENTS 9/1943 Popp 2'2060 X 9/1956 Hoch 220-4 OTHER REFERENCES IBM Technical Disclosure Bulletin, page 8, vol. 5, No. 1, June 1962, Container, L. F. Foylinand and D. G. Leek.

THERON E. CONDON, Primary Examiner. G. E. LOWRANCE, Assistant Examiner. 

